Numerous industries, such as oil and gas production and refining, chemical, food processing and water treatment industries, utilize dry, dusty materials which are packaged in bags. The bags may be made of paper, plastic or fabric, and typically weigh one ton, or more. Many applications for such bags require the bag to be lifted to a great height to be dispensed into an opening at the top of a container. For example, the use of bags of a consumable material to clean up various natural gases in H.sub.2 S reactors is known. Such reactor vessels typically have an upwardly extending column terminating in a manway into which the consumable material is added.
In order to put the contents of the bag into such reactor vessels, the bag is hoisted by a crane above the open manway on top of the reactor vessel column--sometimes as much as 40-50 feet above ground level. Two workers on a walkway, one to hold the bag steady and one to pull a release string and retrieve a plastic spout, empty the bag into the manway while it is being held in place by the crane. The plastic spout is typically very short--12-22 inches--which requires that the bag must be held very close to the opening before the spout is released. The release of the spout above the manway produces dust. Moreover, should the crane falter or fail during the time a worker's arms are under the bag, serious injuries could result. For that reason, safety inspectors have curtailed this operation and have required that a better way of handling the bags during the dumping operation be found.
Several prior patents disclose apparatus and/or methods for breaking bags for emptying into a container. U.S. Pat. No. 4,332,334, issued to Mian, shows a relatively complex, dustless bag breaker having a square box-shaped container covered with a hinged lid. The bag breaker includes an annular flange with bolt holes for mounting to the receptor vessel. A rotatable blade-like cutter is provided within the container and rotates on a shaft which also turns one or more flappers for striking the bag to urge the material out. This assembly is quite bulky and detrimentally requires power, a motor and a drive train to operate.
In U.S. Pat. No. 4,527,716, issued to Haas, et al., an apparatus for dispensing material from a bag utilizing a discharge tube having a pointed end is shown. The tube includes a flange for ostensibly forming a seal around the hole created by the pointed end and the material then is dispensed from the bag through the tube. However, this apparatus is not dust-free, and the time required for fully emptying the bag through the tube is quite long. Furthermore, a certain amount of the consumable material remains around the pointed end of the tube at the bottom of the bag, prior to withdrawing the tube, and is thus wasted.
U.S. Pat. No. 4,557,825, issued to Wittes, et al., shows a bag breaking device which mounts to the top of a tank into which abrasive material is dispensed. The device includes two connected V-shaped bars with their apexes pointing up onto which the bag is dropped. A bolt extends through the bars at the apex to facilitate puncturing of the bag. A grate covering a hole in the vessel is mounted below the bars so that the bag will be torn open and the contents dispensed through the grate into the container. This design does not provide for positioning of the bag over the bag breaking device, which can be a difficult operation for heavy bags hoisted with a crane high above a vessel. Additionally, due to the settling of abrasive material around the hole, it is likely that some remains in the bag and does not enter the vessel. The remaining material will then be lost when the bag is lifted off the tank, undesirably producing dust in the process.
Prior arrangements for emptying bags of material into vessels share another disadvantage in that the time required to locate the bag over the vessel opening and dispense the material is excessive and thus costly. Specifically, a crane is commonly used to hoist the bag over the vessel, the crane being rented or leased. The present bags having a drawstring and integral plastic spout must be precisely located over the vessel opening by the crane operator and then the drawstring released and spout unfurled by a worker on the vessel to dispense the material. The entire operation may take three to five minutes to empty the bag, which is costly when a large number of bags are being emptied into the vessel at once. In some instances, fifty bags may be emptied at once resulting in a total crane rental time of more than four hours.
With these and other disadvantages of the prior art in mind, the present invention discloses a novel bag opener and dispenser for mounting onto container openings located at heights requiring a crane to lift the bag.